Rear Diff Fill Plug

[DanD]

I want to remove the rear differential fill plug on my 03 Trailblazer. I had it out probably 4 or 5 years ago when I changed oil and at that time I put anti-sieze on the threads and torqued it to the proper level (30 or 35 ft. lbs I believe). So, it shouln't be too frozen. Guess I should check it more often but with absolutely no leaks, it's something that's easily put off. Went to take it out the other day and it didn't want to move. I didn't get a lot of power on it though. I was just using a 3/8" extension but it felt like it was starting to slip so I just quit before doing damage. Anyway, my question is this... is that hole in the plug actually 3/8" or is it 10 mm? 10 mm is about .020" larger than 3/8" and using just a little bit too small of a wrench for that could be bad. It would be surprising to me to find out that this was actually a 3/8" hole when every other nut, bolt, fastener and drain plug that I know of on the vehicle is metric. Anyone know for sure? Either way I will get a proper pipe plug socket. Do they really grip a lot better than a ratchet extension? Would it be wise to get one that could be used with an impact wrench or not necessary? What is the overall diameter of the plug? Will maybe get a new one if I get the old one out. Thanks in advance. I searched for the answer here before posting, but didn't find this informmation.

 

[The_Roadie]

It's 3/8" Odd, but it was the standard. Using an impact on the proper tool (the ratchet extension has an unwanted rounded bottom you could grind off) is a lot more reliable than any amount of force by way of a breaker bar.

 

[Wooluf1952]

It's 3/8" Odd, but it was the standard. Using an impact on the proper tool (the ratchet extension has an unwanted rounded bottom you could grind off) is a lot more reliable than any amount of force by way of a breaker bar.

That's what I did. I had an extra 1/2" to 3/8" adapter and ground the bottom flat.

 

[jpinoy]

I actually just picked one of these up from Amazon, works great and prime shipping, if you have that..

http://smile.amazon.com/gp/product/B0076HIV3S/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

and, if you need extra leverage, just put a box end wrench on the end of that ratchet and give it a good push, worked for me.

 

[BrianF]

When it came time to do mine it was frozen as well. I bought mine used with 25,000km on it. Someone previous tried to remove it and began rounding the plug out. I was unable to get it loose without the 3/8 extension popping out. I went to a local mechanic who refused to look at it. He told me, in know way would I charge you money for something you can try at home. He was right. I used the same extension, tapped it in and then with a snipe I tightened it. I easily moved, no drama what so ever. I then removed it.

 

[DAlastDON]

When it came time to do mine it was frozen as well. I bought mine used with 25,000km on it. Someone previous tried to remove it and began rounding the plug out. I was unable to get it loose without the 3/8 extension popping out. I went to a local mechanic who refused to look at it. He told me, in know way would I charge you money for something you can try at home. He was right. I used the same extension, tapped it in and then with a snipe I tightened it. I easily moved, no drama what so ever. I then removed it.

Glad you got it out. Most of the time when faced with a stuck nut, bolt, screw, etc... Tighten it a little bit before trying to loosen it will help free it up if it is seized.

 

[carshinebob]

I brought this thread back to say "Thanks" to the_roadie. I've been putting off changing the rear diff fluid because the fill plug is almost rounded out from before I owned it. With my die grinder, I made a nice tight fitting tool out of an old half inch extension. Then using my impact, popped it right out. It surely would have rounded out with a breaker bar. Thanks again. ~BOB